Résumé:
The environmental concerns about greenhouse gases and the consequent climate change urge the transition towards cleaner, renewable energy sources. Solar energy applications are promising to play an important role in energy transition, especially photovoltaics (PV) and concentrated solar power (CSP) technologies. CSP plants are of interest, particularly solar tower plants, thanks to the possibility of reaching high temperatures, and thus more important efficiencies. The Algerian Sahara has a high potential to host solar projects in general and CSP ones in particular thanks to its high annual levels of incident, direct solar irradiance, and there already are pilot projects to assess this potential, however, the environmental hostility of the Sahara requires the prior evaluation of the possible optical losses suffered by solar mirrors due to the presence of high aerosols’ loads and dust particles. Such particles would attenuate considerably the incident solar energy, either by atmospheric extinction due to suspended particles, or due to the deposition of these soiling particles on the surfaces of solar mirrors.
In the present thesis, we make a first step towards the evaluation of reflectivity losses of solar tower’s heliostats under Saharan climate (since this issue has never been studied in Algeria), and this through the first outdoor heliostats’ soiling campaign at a CSP-suitable site in the province of Laghouat, we also explore soiling mitigation approaches that are water-economic such as coatings. To do so, we used an experimental setup to expose several solar mirrors to outdoor arid climate conditions of Laghouat city. The trends of the measured reflectivity are consistent with the theoretical and bibliographic background. Also, the physical and chemical properties of dust particles -deposited on the mirrors- are investigated through the characterization by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-rays diffraction (XRD), the desired properties were investigated in the Technical Platform for Physical and Chemical Analysis (CRAPC-PTAPC) located in Laghouat as well, next to where the experimental setup was installed. Another important contribution of the present thesis is publishing the first paper to review the literature of dust-related problems for CSP, unlike photovoltaic technology which benefited from multiple reviews. In our future work, we plan to geographically extend the present study for the purpose of assessing the potential of different Algerian regions to host concentrated solar power plants in general, and solar tower projects in particular.
